JP2000239451A - Rubbery material and hose for co2 refrigerant - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a rubbery material which does not show affection such as swelling or foaming by supercritical CO2 and satisfied requirement for CO2 gas barrier by specifying elongation at break (EB) of a material including a non-polar rubber and a blended material thereof used in contact with supercritical CO2. SOLUTION: A rubbery material is a non-polar rubber (a rubber having a polar group in a molecule) or a blend of not less than two non-polar rubbery rubbers which shows elongation at break of not less than 200%. Such example includes ethylene-propylene-diene rubber (EPDM) and butyl rubber (IIR). A hose for a CO2 refrigerant comprises a rubbery inner layer 2 (EPDM), a CO2 gas barrier layer 3 obtained by spirally winding a metal foil seal 3a laminated with a polyamide, a reinforcement layer 5 obtained by braiding a reinforcement yarn via an intermediate rubbery layer 4 (IIR) and a rubbery outer tube layer 6 (chloroprene rubber).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a supercritical C0
Rubber material to be used under conditions that may contact _2, and a C0 ₂ refrigerant hose using the rubber material.

[0002]

2. Description of the Related Art Conventionally, refrigerants used in various cooler systems, such as car coolers and indoor air conditioners, are mainly Freon-based or alternative Freon-based refrigerants, and these gases permeate through refrigerant hoses to the atmosphere. In view of the atmospheric ozone depletion effect in the case of C0 ₂ and the like, C02 refrigerant has recently attracted attention.
C0 ₂ refrigerant, compared with fluorocarbon refrigerant such as greenhouse gas released into the atmosphere has the advantage of reducing the about one-third. However, it unnecessarily the complicated refrigerant supply to the cooler system, the demand for equal, it is also C0 ₂ transmission suppressing in the refrigerant hoses can not be underestimated problem.

[0003] On the other hand, many refrigerant transfer hoses that are piped in various conventional cooler systems basically have a structure in which a fiber reinforcing layer is interposed between an inner rubber tube and an outer rubber tube. In view of the further improvement in refrigerant impermeability in consideration of C0 ₂ refrigerant having high permeability and the like, an increase has been made.

[0004] In the rubber inner tube of these refrigerant transport hoses, it has been mainly expected to ensure a durable sealing property of a pipe connection portion of the hose, a refrigerant permeation resistance in the rubber inner tube, and the like. Therefore, the selection of the rubber material constituting the rubber inner tube is also studied exclusively from these viewpoints, and it is difficult to say that the shape, structure or performance of the rubber inner tube changes in a short term and dramatically by the action of the refrigerant. It was not expected.

[0005]

According to the SUMMARY OF THE INVENTION However the study of the present inventors, in a cooler system using a C0 ₂ refrigerant, actually at the time of its operation (refrigerant pressurized) C0
₂ may result in the supercritical state (a state in which the liquid and gas is a single phase), depending on the material of the inner rubber tube, the expansion in a short time inner rubber tube by C0 ₂ working in a supercritical state, further Has been found to be subject to the dramatic change of foaming. When the rubber inner tube is subjected to such a change, not only the pressure resistance performance of the hose is significantly impaired, but also the hose line may be reduced or blocked, and the sealing performance expected at the rubber inner tube is expected. Etc. can be compromised.

[0006] The present invention is expanded by C0 ₂ in supercritical conditions, less susceptible to changes in the foam, such as (or be subject to slight changes, easy to return to the original state when the cooler system inoperative), and C0 ₂ gas providing an impermeable be compatible rubber material required physical properties from conventional like, further, provides a C0 ₂ refrigerant hose configured to a preferred multilayer structure with use of the above rubber in a rubber tube Is the task to be solved.

[0007]

SUMMARY OF THE INVENTION (Configuration of the first invention) The configuration of the first invention for solving the above problems (claim 1) may be brought into contact with the C0 ₂ in the supercritical state A rubber material used under conditions, comprising a blend of one or more non-polar rubbers, and having a tensile elongation at break (EB) of 200% or more.

(Structure of the Second Invention) The structure of the second invention of the present application (the invention described in claim 2) for solving the above problems is as follows.
The non-polar rubber according to the first invention is ethylene-propylene rubber (EPM), ethylene-propylene-diene rubber (EPDM), butyl rubber (IIR), chlorinated butyl rubber (Cl-IIR) or brominated butyl rubber (Br-IIR).
Is a rubber material.

(Structure of Third Invention) The structure of the third invention (the invention described in claim 3) for solving the above-mentioned problem is as follows.
The rubber material according to the first or second invention is a rubber material having a CO ₂ gas permeation amount of 50 or less as a relative index when natural rubber (NR) is set to 100.

(Structure of the Fourth Invention) The structure of the fourth invention of the present application (the invention according to claim 4) for solving the above problems is as follows.
Metal foil layer, and having a C0 ₂ gas impermeable layer having a metallized layer or a resin layer, on the inner circumference of the whole or at least a pipe connecting portion, rubber material according to any one of the first to third aspects of the invention having a rubber inner tube layer with a C0 ₂ refrigerant hose.

(Structure of Fifth Invention) The structure of the fifth invention of the present application (the invention according to claim 5) for solving the above problems is
A C0 ₂ gas impervious layer according to the fourth aspect of the present invention, which is provided with an intermediate rubber layer, a reinforcing layer, and a rubber outer tube layer sequentially around the outer periphery of the C0 ₂ gas impermeable layer;
_{2 This is a} refrigerant hose.

[0012]

[Action and Effect of the Invention] (Action and Effect of the First Invention) As a result of the experiment, a so-called polar rubber is generally found to have a C0 in a supercritical state.
_When immersed or contacted in _2, it is susceptible to dramatic deterioration such as relatively significant expansion and foaming within a short time, and the occurrence of bursting flaws generated by bursting of the foamed part, and It was found that not only the foam rupture flaws but also changes such as expansion and foaming were difficult to return to the original state. Accordingly, even when the system inoperative to the cooler system C0 ₂ is returned to the following conditions critical point, the rubber material is hard to restore the original condition.

Meanwhile, the non-polar rubber and the blend material is typically, only causing a relatively mild inflated by C0 ₂ in the supercritical state and the supercritical state of the expansion also C0 ₂ is released It was also found that the tendency to return to the original state quickly was remarkable, especially when the tensile elongation at break (EB) of the rubber material was 200% or more.

[0014] Rubber material of the first invention, the supercritical C0 ₂
Although it is used under the condition that it can come into contact with a non-polar rubber, one or two or more kinds of nonpolar rubbers having a tensile elongation at break (EB) of 200% or more are used. _{Due to (2)} , it is hard to suffer deterioration such as remarkable expansion, foaming and foam rupture flaws, and easily returns to the original state even if relatively slight expansion occurs.

[0015] Therefore, when using the rubber material of the first invention in a rubber tube layer of C0 ₂ refrigerant transporting hose, the hose pipe based on the expansion and foaming of the rubber material reduced or blockage, the pipe connecting part Inconveniences such as impaired sealing performance can be avoided in a durable manner. Also, such non-rubber inner tube layer, even when using for applications under conditions which contact the C0 ₂ in the supercritical state,
Various inconveniences caused by the expansion, foaming, and foam rupture of the rubber material can be avoided in a durable manner.

(Operation and Effect of Second Invention) As in the second invention, the non-polar rubber is ethylene-propylene rubber (EP
M), ethylene-propylene-diene rubber (EPD)
M), butyl rubber (IIR), chlorinated butyl rubber (Cl-
IIR) or brominated butyl rubber (Br-IIR), the operation and effect of the first invention are particularly remarkable.

(Function / Effect of Third Invention) In the third invention, the CO ₂ gas permeation amount of the rubber material is 30 × 10 ^-9 cm ³
・ Because a material having a density of not more than cm / cm ² · sec · cmHg is used, its CO ₂ gas impermeability is originally large, and furthermore, significant expansion, foaming, generation of foam rupture flaws due to contact with supercritical CO ₂ etc. Since it hardly occurs, a high CO ₂ gas impermeability can be maintained durably.

[0018] In (Operation and Effect of the fourth invention) fourth invention, since providing the C0 ₂ gas impermeable layer having a predetermined configuration C0 ₂ refrigerant hose, passes through the tube wall of the hose in the radial direction C0 _{(2) The} amount of gas permeation can be significantly reduced.

[0019] Then C0 to the inner periphery of the whole or at least the pipe connections ₂ gas impermeable layer, the first invention to third rubber material rubber inner tube layer is provided using according to the invention, the sealing of the pipe connection portion Is effectively ensured, and C0 in the supercritical state
Deterioration of the rubber inner tube layer due to ( ₂₎ can be avoided in a durable manner, and there is no possibility that the rubber tube tube will be significantly expanded and foamed, and the hose conduit will be reduced or blocked.

Further, when the CO ₂ gas permeation layer in the radial direction of the hose tube wall is highly blocked by the CO ₂ gas impermeable layer,
Furthermore, although the effective suppression of C0 ₂ gas permeation amount that passes through the pipe connecting portion in the axial direction along the inner rubber tube layer is desired, durably this effect without rubber material is deteriorated due to C0 ₂ in the supercritical state To secure.

[0021] Thus C0 ₂ refrigerant hose of the fourth invention,
To particular highly permeable C0 ₂ refrigerant as compared to the CFC-based or HCFC-based refrigerant, very high C as a whole hose
O ₂ gas impermeability can be realized in a durable manner.

[0022] by (Operations and effects of the fifth invention) fifth invention, practically excellent one embodiment of the C0 ₂ refrigerant hose according to the fourth invention is provided.

[0023]

Next, embodiments of the first to fifth inventions will be described. In the following, simply "the present invention"
When it says, it refers to 1st invention-5th invention collectively.

[0024] [application of rubber material] Rubber material according to the first to third aspects of the invention is not limited to application to the extent that is used under conditions that could be brought into contact with the C0 ₂ in the supercritical state. The most typical applications, the fourth invention or is a use of the inner rubber tube layer in C0 ₂ refrigerant hose according to the fifth invention, C0 ₂ refrigerant hose having no these C0 ₂ gas impermeable layer May be used for the rubber inner tube layer.

[0025] Also, any member of the cooler system the C0 ₂ as a refrigerant, or C0 ₂ is at any other device or system which can be a supercritical state, is used under conditions that may contact with the C0 ₂ ( For example, it may be used as a constituent material of a seal member (O-ring) or the like.

[Type and Composition of Rubber Material] The rubber material used in the present invention is a blend of one or more of so-called non-polar rubbers (rubbers having no polar group in the molecule). Elongation at break (EB) is 200% or more.

Of these, EPM, EPDM, IIR,
Cl-IIR, Br-IIR, natural rubber (NR), butadiene rubber (BR), styrene-butadiene rubber (SBR)
Etc. are more preferable in view in particular less deteriorated by C0 ₂ in supercritical conditions, especially EPM, EPDM, IIR, Cl @ -
IIR or Br-IIR is C0 ₂ gas impermeability even particularly preferable in that they are very good. Also preferred are blends of two or more of the various rubbers specifically listed above.

To these non-polar rubbers, various known or commonly used additives such as carbon black, process oil, vulcanizing agents, vulcanization accelerators, antioxidants and the like can be appropriately added. it can. However, for example, the addition of carbon black can affect the tensile elongation at break (EB) of the rubber material, so it is better to pay attention to the optimal design of the type and the amount of addition.

Of the above various rubber materials, those having a tensile elongation at break (EB) of not less than 200% are those in the supercritical state.
Even when immersed or in contact with O ₂ , it is hardly deteriorated,
preferable. More specifically, merely inflated relatively lightly by C0 ₂ in the supercritical state, without causing significant expansion, it is not observed such occurrence of foaming or foam rupture flaws. The expansion even reversible, to return rapidly to non-expanded state when the supercritical state of the C0 ₂ is released.

[0030] Even the various rubber materials, for example, when the breaking elongation tensile by excessively adding carbon black (EB) is such that less than 200%, relatively the C0 ₂ in the supercritical state Significant swelling (or
C0 ₂ in supercritical state is also released which may quickly produce hardly expanded) to return to the non-expanded state.

[C0 ₂ Refrigerant Hose] The C0 ₂ refrigerant hose has at least a C0 ₂ gas impermeable layer described later, and a rubber inner tube using the above rubber material at all or at least a pipe connection portion of its inner periphery. Anything having a configuration having a layer is sufficient.

The C0 ₂ refrigerant hose may optionally comprise other components other than the above. For example, C0 ₂ providing a reinforcing layer on the outer peripheral side of the gas impermeable layer, an intermediate rubber layer between the reinforcing layer and the C0 ₂ gas impermeable layer, or the outer rubber on the outer peripheral side of the reinforcing layer For example, providing a tube layer. It is conceivable to provide an intermediate rubber layer between the rubber inner tube layer and the CO ₂ gas impermeable layer, but the rubber inner tube layer is not provided on the entire inner periphery of the CO ₂ gas impermeable layer as described later. case, it is better not to provide also the intermediate rubber layer (to avoid contact with the C0 ₂ refrigerant).

The type and specific configuration of the materials used in the components such as the intermediate rubber layer, the reinforcing layer, the rubber outer tube layer and the like are arbitrary. Butyl rubber (IIR), nitrile rubber (NBR), chlorosulfonated polyethylene rubber (CSM), etc., and ethylene-propylene-diene rubber (EPDM), butyl rubber (IIR), chloroprene Rubber (CR), chlorosulfonated polyethylene rubber (CSM) and the like can be used. As the reinforcing layer, a wire braid layer, a reinforcing yarn braided or two layers spirally wound in the opposite direction, and an intermediate rubber layer interposed between two spiral layers wound in the opposite direction, etc. Can be used.

[CO ₂ gas impermeable layer] The CO ₂ gas impermeable layer is provided directly on the outer peripheral side of the rubber inner tube layer made of the above rubber material or via the first intermediate rubber layer or the like. And at least a metal foil layer, a metal deposition layer or a resin layer.

The structure of the above-mentioned metal foil layer or metal vapor deposition layer is not limited as long as it includes at least a metal foil or a metal vapor deposition film. For example, (1) metal foil, (2) metal foil and reinforcing material, (3) A) A metal-deposited film formed on a base material such as a resin film may be used as a core material, and a resin film may be laminated on the core material and bonded or thermally fused to form a laminate sheet.

In particular, the laminated sheet is once formed in a tape shape, and is then formed into a so-called spiral winding or longitudinally wrapping (a winding method in which the tape-like laminated sheet is wound in parallel with the hose in the axial direction). By slightly polymerizing the widthwise ends of the tape-like laminate sheet at the time,
A method of forming a unbroken C0 ₂ gas impermeable layer as a whole is preferred. It is more preferable that the above-mentioned superposed portions of the tape-like laminated sheets are adhered to each other.

The material of the above resin film is not limited, but preferably a thermoplastic resin such as polyamide resin (PA), polyethylene terephthalate resin (PET), ethylene vinyl alcohol copolymer resin (EVOH) can be used. Although the type of the above-mentioned reinforcing material is not limited,
Preferably, a reinforcing material having high elongation resistance and excellent flexibility, such as a wire mesh, a reinforcing cloth material (especially a canvas made of aramid fiber, carbon fiber, glass fiber, or the like, a nonwoven fabric, etc.), a high-strength resin film, or the like is used. be able to.

[Rubber inner tube layer]
It is constituted by the rubber material according to any one of the third inventions, and C0
₍₂₎ The innermost layer of the refrigerant hose,
It is formed on the entire inner periphery of the O ₂ gas impermeable layer or at least on the pipe connection.

[0039] From the viewpoint of ease of formation of the inner rubber tube layer, it is advantageous to provide the inner rubber tube layer to all of the inner periphery of the C0 ₂ gas impermeable layer. The thickness of the rubber inner tube layer may be arbitrarily designed as required, and may be, for example, about 0.5 to 2.0 mm.

[0040] In the configuration example shown in FIG. 1 [Configuration example of a C0 ₂ refrigerant hose], C0 ₂ refrigerant hose 1, in order from the innermost layer, inner rubber tube layer 2, C0 ₂ gas impermeable layer 3, an intermediate rubber It has a multilayer structure composed of a layer 4, a reinforcing layer 5, and a rubber outer tube layer 6.

The inner rubber tube layer 2 is formed using EPDM having a tensile elongation at break (EB) of more than 200%. The CO ₂ gas impermeable layer 3 on the outer periphery of the rubber inner tube layer 2 is a tape-shaped laminated sheet 3 in which a metal foil is sandwiched between polyamide resins.
a is spirally wound around the outer periphery of the inner rubber tube layer 2. C0 The _second gas periphery impermeable layer 3, through the intermediate rubber layer 4 made of IIR, the reinforcing layer 5 formed by knitting blade reinforcing yarn is provided, further rubber outer tube layer made of CR on its outer periphery 6 are provided.

[0042]

EXAMPLES (Preparation of Rubber Specimen) Tables 1 and 2 at the end
Of the rubber shown in the column of "Polymer type" in each item, as shown in the column of "Components" in each table, 100 parts by weight of each unvulcanized rubber (shown as "polymer" in the table) Additives were added in the indicated numerical parts by weight, kneaded according to a conventional method, and vulcanized and formed into a sheet having a thickness of 2 mm.
In each table, "promoter TT, CZ, DM" indicates "tetramethylthiuram disulfide, N-cyclohexyl-2-benzothiazylsulfenamide, dibenzothiazyldisulfide", respectively, and "organic peroxide". (Parkmill D) "is dicumyl peroxide manufactured by NOF Corporation.

Then, the sheet-shaped vulcanized molded product according to each of the above examples was cut into a square of 100 × 100 mm to obtain a rubber material test piece according to each of the examples, and was subjected to the following evaluation.

(Initial physical properties) As the initial physical properties of the rubber test pieces of each example, the tensile strength TB (MPa) and the tensile elongation at break EB (%) were measured according to JIS K 6521.
Tear strength Tr (N / mm) according to K 6252
Was evaluated, and the results are shown in Tables 1 and 2.

From these results, it can be seen that the rubber test pieces of each example show a tensile elongation at break of about 200% or more.
As shown in items IIR and IIR, it was found that the tensile elongation at break decreased when the amount of carbon black added was increased, and in particular, when a large amount of carbon black was added, the tensile elongation at break was less than 200%.

Further, based on the ASTM D-1434-75M method, a gas per unit thickness of the rubber material test piece according to each example was measured by a GTR gas permeation measuring device using CO ₂ gas under the condition of 80 ° C. Transmission coefficient (× 10 ^-9 cm ³
Cm / cm ² · sec · cmHg). The results are shown in the column of “CO ₂ gas permeability” in Tables 1 and 2. The rubber material other than NR, SBR and BR was 30 × 10 ^−9.
A satisfactory value of not more than cm ³ · cm / cm ² · sec · cmHg was shown.

[0047] The (supercritical C0 ₂ immersion treatment in gas) rubber test piece of each example was tightened lid bolts were placed in each of a stainless steel autoclave. Was then filled with liquefied C0 ₂ therein, allowed to warm to autoclave C0 ₂ critical points (31 ° C or higher /7.39MP
a) and a C02 supercritical state of 35 ° C. × 8 MPa exceeding the above condition, and the rubber material test piece was treated in this state for 30 minutes.

(Evaluation of foaming and expansion after immersion treatment) Thereafter, the inside of the autoclave was gently depressurized and returned to normal temperature and normal pressure, and then a rubber test piece was taken out. , 10 minutes and 24 hours later, the surface of the foamed state was visually observed, and the degree of expansion was measured. In the observation of the surface in the foaming state, a sample having no or almost no foaming was indicated by “○”, a sample having a large number of foams indicated by “×”, and a sample having a foam rupture defect indicated by “*”. On the other hand, the degree of swelling was obtained by measuring the dimensional change before and after the treatment, obtaining the volume change, and expressing the increase in%.

According to the evaluation results shown in Tables 1 and 2, CPE, NBR, ACM, and FKM have a large degree of expansion, and many foams are observed (foaming does not disappear even after 24 hours). Foam rupture flaws occurred, but NR, SB
R, BR, EPDM, IIR, Cl-IIR, Br-IIR
Had a relatively small degree of expansion and no foaming or foam rupture flaws were observed.

(Evaluation of physical properties after immersion treatment)
0 ₂ per rubber specimens of each example after immersion treatment in a gas, the "initial properties" strength T tensile in the same way as for
B (MPa) and tensile elongation at break EB (%) were evaluated. However, for CPE, NBR, ACM, and FKM, effective measurement could not be performed because of foam rupture flaws and was not evaluated.

According to the evaluation results shown in Tables 1 and 2, EPDM and Cl-IIR containing a large amount of carbon black were added.
With regard to the rubber test piece, the tensile elongation at break EB is slightly lower than the initial evaluation.

[0052]

[Table 1]

[0053]

[Table 2]

[Brief description of the drawings]

1 is a diagram showing a configuration example of a C0 ₂ refrigerant hose.

[Explanation of symbols]

1 C0 ₂ refrigerant hose 2 rubber inner tube layer 3 C0 ₂ gas impermeable layer 3a laminate sheet 4 intermediate rubber layer 5 reinforcing layer 6 outer rubber tube layer

Continued on the front page F-term (reference) 3H111 BA01 BA12 BA34 CB06 CB14 CC02 DA26 DB09 4F100 AB01B AB33B AD11D AG00D AK01B AK09A AK09J AK28A AK28J AK42B AK46B DAAKA BAB BAK BAA BAA BAE BAA JB01A JD02A JD02B JK08A YY00A 4J002 BB15W BB15X BB18W BB18X BB24W BB24X GM01

Claims (5)

[Claims] 1. A rubber material to be used under conditions that could be brought into contact with the C0 ₂ in the supercritical state, made from either one or two or more of the blend material of the non-polar rubber, and a tensile elongation at break ( EB) is 200% or more. 2. The non-polar rubber is ethylene-propylene rubber (EPM), ethylene-propylene-diene rubber (EPDM), butyl rubber (IIR), chlorinated butyl rubber (Cl-IIR) or brominated butyl rubber (Br-IIR).
The rubber material according to claim 1, wherein 3. The rubber material according to claim _2, wherein the CO ₂ gas permeation amount is 30.
^3. The rubber material according to claim 1, wherein the rubber material has a pressure of not more than × 10 ⁻⁹ cm ³ · cm / cm ² · sec · cmHg. Wherein the metal foil layer, and having a C0 ₂ gas impermeable layer having a metallized layer or a resin layer, on the inner circumference of the whole or at least a pipe connecting portion, any one of claims 1 to 3 A hose for a CO ₂ refrigerant, comprising a rubber inner tube layer using the rubber material described in 1 above. The outer periphery of claim 5, wherein the CO ₂ gas impermeable layer, successively, an intermediate rubber layer, C0 ₂ refrigerant hose of claim 4, characterized in that it comprises a reinforcing layer and outer rubber tube layer.